Electron discharge device



T. T. EATON 2,416,914

ELECTRON DISCHARGE DEVICE Filed July 50, 1943 Ihwentor T UmHT. Emon 2 5 I? (Ittorneg Paiented Mar. 4, 1947 STATES ELECTRON DISCHARGE DEVICE Thomas T. Eaton, Haddon Heights, N. J., assignor to Radio Corporation of America, a corporation of Delaware 13 Claims.

This invention relates to electron discharge devices and particularly to so called plural-beam cathode ray tubes.

Cathode ray tubes are known wherein a signal is put on a storage screen by one electron beam and taken off the screen by a second electron beam. Such tubes find useful application, by way of example, in radar and other systems for the communication of intelligence where they may be employed to improve the signal-to-noise ratio by averaging-out undesired components from.

the signal-bearing pulses or waves.

The storage screens used in such tubes have heretofore comprised either a two-sided mosaic, in which case the put-on and take-off beams are directed upon opposite sides of the screen (see British Patent 501,179), or a s ngle-sided caes ated screen of a special (commutator-type) laminated construction. In this latter case both beams usually impinge the same side of the screen, preferably at difierent velocities (as to th s, s e cooend ng application Serial No. 492,658. filed June 26, 1943).

Irrespect ve of the advantages claimed for the plural beam tubes of the prior art, it may be sa d, generally, that the insulation and other problems inc dent to the c nstruction and use of their mosa c tyne or commutator type signal-store r des renders such tubes more expensive and difiicult to manufacture and service than is ne ess r or d sirable.

Acc rd n ly. an im ortant object of the present invention is to rovide an improved cathode ray tu e i cor ora in a sig al-storage electrode of a n el onstr ction whic ((1.) presents substa ti lly no insulation problems either in its manufact re or use. and (b) dispenses entirely with cae ium and o her activating agents.

Anot er and rel t d object of the present invention. is to rovide a simple. inexpensive and troublafree plural-beam cathode ray tube and one capable of avera in -out undesired compo ents from the signal waves or pulses in radio, radar an alogcus systems for the communication of intelligence.

Other objects advan ages will be ap arent and the invention itself will be best understood by reference to the following specification and to the accompanying drawing. wherein Fig. l is a perspective View of a plural beam tube constructed in accordance with the principle of the invention and showing certain electrical connections thereto,

Fig. 2 is an enlarged end view of one of the resistive supports for the slat-like armature or electrodes of Fig. 1,

Fig. 3 is a plan view of the slatted masking electrode of Fig. 1 and showing how the beam from the vertical electron-gun is deflected, and

Fig. 4 is a plan View showing an alternative target electrode assembly.

In Fig. 1 of the drawing, i designates the bul ous portion of a highly evacuated tube or envelope having two hollow neck portions 3 and 5 each of which contains an electron gun, l and respectively, which are directed inwardly to the center of the bulb along axes spaced substantially apart. As in standard practice, grounded metallic coatings II and iii on the inner surface of the tube serve as the second anodes for these guns '2 and The gun i is provided with a single pair of deflecting plates E5 which are arranged to move the electron beam, which passes therebetween, to and fro across a number of spaced metal strips i'ia, ilk, which are supported in a common plane normal to the axis of the gun i on two root-like members comprising separate wires 89, it, coated with a resistive material, I97 (Fig. 2), such for example as carbon or graphite. A metal plate 25 is supported behind the spaced metal strips 9 in a plane parallel to the plane of said strips and spaced therefrom. This metal plate 2! is in useful capacitive relation with the several spaced metal strip No, i lit and thus may be said to comprise a. common armature for a number of discrete capacitors which are connected (in parallel relation) to ground through the carbon resistors @922 The use of the common armature 2i for all these capacitors obviously is to be preferred to the use of number of separately paired armatures.

The electron beam 23 (see Fig. 3) from the ther gun 9 is directed into and scans the vacuous space between the back plate is?! and the strip-like structure ii. To this end, the gun 9 is provided with a pair of deflecting plates 25 and a second pair of plates 2? which may be employed in centering said beam. This beam 23 is directed toward a collector electrode 29 which is mounted behind a longitudinal slot 3E0, in a masking plate 3! which is mounted in a plane n rmal to the axis of the gun 53 on the remote side of the said inter-armature space. t will be observed that the metal strips or armatures ila, ilk are arranged like the sticks of a fan whose pivot or center lies adjacent to the deflector plates 25 of the electron gun 9. Thus the electron beam 23 from the gun 9 in sweeping the vacuous space between the armatures Il2l will not be in register with more than one of the metal strips Ila, I'Ib, etc. at any given moment. It is therefore apparent that if this beam 23 is deflected at any given point within the said space the deflection will be a function of the charge upon the particular armature (Ila or I'll), etc.) with which the beam is in register at the moment it is deflected.

As indicated in Fig. l the relative potential distribution amon the electrodes is preferably (but not necessarily) as follows: The several armature Strips l'ia, l'lb, etc. are connected through the resistive material I91", and wires l9, ii! to ground. The common armature or back plate 2! and the masking electrode 3| are maintained slightly negative with respect to ground, as by the batteries 33 and 35, respectively. A third battery 3i connected to the centering electrodes 21 serves to position the beam 23 from the electron gun 9 with respect to the slot 3la in the masking electrode 3 l The deflecting electrodes 25 for the gun 9 are connected to a suitable deflecting circuit (not shown) but which will b understood to have a time cycle sufficiently rapid to ensure persistence of vision when the target electrode 29 is connected (as through a resistor 39) to an image tube, not shown.

The signal-bearin noise-affected pulses or waves are applied to the grid of the first gun l, and the beam from the said gun, thus modulated, is moved rapidly to and fro across the capacitor strips H 1. l fe, in synchronisin with the received pulses by the deflecting circuit which is connected to the horizontal deflecting plates l5. It is apparcut that since the strips Ila, l'lk are connected to ground through the resistors I97 each strip will accumulate an electron-charge (from the beam) which is of average intensity. That is to say, the charge on each strip is not the result of a single excursion of the beam but is the result of many excursions. Now, since the noise peaks tend, over a period of time, to be of a uniform average intensity, it is apparent that the charge on each strip in any given period (of sufficient length) will tend to be the same intensity and f T the other will tend to deflect the beam 23 (from gun 9) a definite lateral distance with respect to the edge of the slot Bid in the masking electrode 3!. Thus, referring now to Fig. 3, if the beam 23 (from the gun 9) is so oriented (by adjusting the potential supplied to its centering electrodes 27 by the battery 3?) that in the absence of signal it will impinge the masking electrode 3! (instead of passing through the slot and) the "noise" will not be transmitted to the output or target electrode 29. On the other hand, when a signal bearing pulse or wave is applied to the grid of the gun l the resulting additional charge developed upon the slot-like armatures Ila, Illa and occasioned by the presence of the signal on the said beam will cause the beam 23 from the other gun (9) to be deflected laterally, so that the said beam passes through the slot 3m in the masking plate 35 and impinges the target electrode 29, thereby recreating only the signal pulse or wave in the output circuit of the device. It is, of course, apparent that if desired the beam 23 may be originally so oriented that it is partly or entirely centered within the slot Sia. In the last mentioned case the added signal (or other pulse or wave or voltage) will cause the said beam to be directed upon the masking electrode 35 rather than upon the target electrode 29.

The fan-shape pattern of the capacitor armatures Ila, ll'k permits of a more compact electrode assembly than would be the case if these slat-like electrodes were all arranged in parallel vertical array, since in the latter case the gun 9 would have to be disposed farther away from the interarmature space if the electron beam is to be prevented from being in register with more than one slat at any given moment.

The invention is susceptible of other modifications. Thus, in some cases it is desirable to prevent the signal-bearing beam from the gun I from passing between the slats Ila, etc. and. impinging the back plate 2l. In this event the slats may be arranged in overlapping relation, for example in the manner indicated in Fig. 4.

Numerous other modifications and applications of the invention will suggest themselves to those Y skilled in the arts to which the invention appertains. Accordingly, the foregoing description of a preferred embodiment of the invention is to be interpreted as illustrative and not in a limiting sense except as required by the prior art and by the spirit of the appended claims.

What is claimed is: a

1. An electron discharge device comprising an evacuated envelope, a plurality of pairs of capacitor armatures mounted within said envelope with one armature of each pair arranged substantially in a common plane and presented in useful capacitive relation across an intervening space to the armature with which it is paired, an electron-gun mounted to project a stream of electrons upon said first mentioned armatures, a second electron-gun mounted to project a beam of electrons through said intervening space along an axis substantially parallel to said common Plane,

and an output electrode assembly mounted on the side of said intervening space which is remote from said second electron-gun and upon which the electrons from said second gun impinge.

2. The invention as set forth in claim 1 and wherein said first mentioned electron-gun is provided with means for directing the stream of e1ectrons therefrom to and fro across the armatures which are mounted in said common plane.

3. The invention as set forth in claim 1 and wherein said second mentioned electron-gun is provided with means for centering the beam therefrom with respect to a selected point upon said output electrode assembly.

4. {he invention as set forth in claim 1 and wherein said second mentioned electron-gun is provided with means for directing the beam of electrons therefrom to nd fro withinsaid intervening space in a direction substantially parallel to said common plane.

5. The invention as set forth in claim 1 and wherein the armatures mounted in said common plane comprise a multiplicity of metal slats arranged like the sticks of a fan whose pivot lies adjacent to the leading end of said second mentioned electron-gun.

6. The invention as set forth in claim 1 and wherein one armature of each pair comprises a common armature.

'7. The invention as set forth in claim 1 and wherein said plurality of pairs of capacitor armatures are connected in parallel.

8. The invention as set forth in claim 1 and wherein resistive means are provided for coupling the armatures in said common plane to ground.

9. The invention as set forth in claim 1 and wherein said output electrode assembly comprises a mask having a slit therein and a target electrode mounted in register with said slit on the remote side of said mask.

10. The invention as set iorth in claim 1 and wherein the armatures in said common plane are mounted in overlapping relation.

lit An electron discharge device comprising an evacuated envelope containing a plurality of pairs of capacitor armatures mounted in substantially parallel planes with one armature of each pair presented in useful capacitive relation across an intervening space to the armature with which it is paired, means for generating and projecting a beam of electrons through said intervening space in a direction substantially parallel to the planes of said armatures, an output electrode assembly mounted in the path of said beam adjacent to that boundary of said space which is remote from the ource of said beam, said output electrode assembly comprising a masking electrode having an aperture therein and a, target electrode mounted in register with said aperture, and means for creating discrete differences in potential among said capacitor armatures whereby to deflect said electron beam laterally with respect to said masking and target electrodes and to thereby proportionately vary the beam current impinging the said electrodes.

12. The invention as set forth in claim 11 and wherein the means for creating discrete differences in potential among said capacitor armatures comprises means for generating and projecting a signal modulated beam of electrons upon one armature of each of said pairsv 13. Method of averaging-out noise from noiseaiTect-ed signal bearing waves in a signaling circult including a plurality of capacitors of the type having spaced apart armatures, said method comprising generating a stream of electrons, directing said stream of electrons longitudinally through said interarmature space toward a target, generating a second stream of electrons, impressing the noise affected waves upon said second beam and rapidly scanning one armature of each capacitor with said second beam to establish an electrostatic field among said armatures proportional to the average of the noise during several excursions of said second beam, adjusting the position of said first mentioned beam so that it is deflected away from its target by the said average electrostatic field and is directed upon said target when said signal bearing waves are applied to said noise affected second electron beam.

THOMAS 'I. EATON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,179,205 Toulon Nov. '7, 1939 2,277,516 Henroteau Mar. 24, 1942 

